The present invention relates to a high frequency treatment instrument to be inserted into an instrument-inserting channel of an endoscope for endoscopic mucosal resection (EMR).
There are various types of high frequency treatment instruments used for EMR. Japanese Patent Provisional Publication No. HEI 7-8503 (hereafter, referred to as a document 1) discloses a high frequency treatment instrument, which includes an insulative flexible sheath and a hook-like electrode located at a tip of the flexible sheath. The hook-like electrode includes a rod-like part elongated frontward from the tip of the flexible sheath, and a hook-like part projected in a lateral direction from a tip of the rod-like part.
The treatment instrument disclosed in the document 1 allows an operator to perform a endscopic treatment easily. However, the treatment instrument has a drawback that the hook-like electrode may accidentally damage an instrument-inserting channel of an endoscope or mucous membranes of a body cavity.
Japanese Patent Provisional Publication No. 2002-153484 (hereafter, referred to as a document 2) discloses a different type of treatment instrument. The treatment instrument disclosed in the document 2 is configured such that the hook-like electrode is retractable with respect to a tip of a flexible sheath. By this structure, the above mentioned drawback of the conventional treatment instrument can be solved.